This invention relates to a method of manufacturing a fluorocarbon-based polymer coating film used on an apparatus or the like requiring a heat-resistant, weather-resistant and wear-resistant coating. The coating can be used on electric apparatuses, such as hot plates and rice cooking machines; vehicles; and industrial apparatus.
Fluorocarbon-based polymer coating films have been used extensively and are manufactured by making the surface of an Al substrate rough by means of a brush or chemical etching; coating the rough surface with a primer or the like; coating with a paint suspending fine particles of a fluorocarbon-based material, such as polytetrafluoroethylene in ethanol or the like; and then drying and baking at about 400xc2x0 C. for about one hour to fix the fluorocarbon-based polymer to the substrate surface of the material.
This method of manufacture is simple. However, since the polymer and substrate are bonded together merely by an anchor effect, there is a limit to the adhesion of the polymer to the substrate. The method is insufficient in view of adhesion and mechanical strength as a method of manufacturing fluorocarbon-based coating films used for apparatus or the like requiring a heat-resistant, weather-resistant and wear-resistant coating. Such electric apparatus include hot plates and rice cooking apparatus; vehicles; and industrial apparatus.
In view of the above drawbacks in the prior art method, it is an object of the present invention to form a fluorocarbon-based coating layer or film having satisfactory adhesion to a substrate that is pinhole-free, thereby improving the performance of an apparatus or the like requiring a heat-resistant, weather-resistant and wear-resistant coating. Such electric apparatuses include hot plates and rice cooking apparatus; vehicles; and industrial apparatus.
The primary objective of this invention is to provide a fluorocarbon-based polymer coating film comprising at least an siloxane film formed as a inner layer and a fluorocarbon-based polymer film formed as an outer layer on the surface of a substrate. The substrate surface and the inner layer are bonded with covalent bonds, and the inner layer and the outer layer are bonded with covalent bonds.
Another objective or this invention is to provide a method of manufacturing a fluorocarbon-based polymer coating film comprising the steps of contacting a substrate having hydroxyl groups on a surface with a non-aqueous solvent containing a material with a chlorosilyl group; coating said substrate surface with either a non-aqueous solvent containing a compound having a fluorocarbon group and a chlorosilyl group or a solvent containing a compound having a fluorocarbon group and alkoxysilane group or a compound represented by the following formula
CF3xe2x80x94(CF2)nxe2x80x94(R)mxe2x80x94SiYq(OA)3-q
where n represents 0 or an integer; R represents an alkyl  alkylene group or a hydrocarbon substituted group containing Cxe2x95x90C, Cxe2x89xa1C, a silicon atom or an oxygen atom; m represents 0 or 1; Y represents a hydrogen atom, an alkyl group, an alkoxy group, a fluorine-containing alkoxy group or a fluorine-containing alkyl group; A represents a hydrogen atom; and q represents 0, 1 or 2; and, and  baking the substrate after the contacting and coating steps.
Another objective of this invention is to provide a method of manufacturing a fluorocarbon-based polymer coating film comprising the steps of contacting a substrate having a surface containing hydroxyl groups with a non-aqueous solvent containing a material having a chlorosilyl group; washing the substrate with a non-aqueous solvent to remove the material without reaction; coating the substrate with either a non-aqueous solvent containing a compound having a fluorocarbon group and a chlorosilyl group or a solvent containing a compound having a fluorocarbon group and alkoxysilyl group.
It is preferable in this invention that both sets of the covalent bonds connecting the substrate surface and the inner layer, and the inner layer and the outer layer are siloxane bonds.
It is preferable in this invention that the inner layer is formed with a siloxane-based monomolecular film.
It is preferable in this invention that the substrate is made from a member of a group consisting of metals, ceramics and plastics.
It is preferable in this invention that the substrate is made of a plastic material treated in a plasma atmosphere containing oxygen.
It is preferable in this method invention that the material having a chlorosilyl group contains a member of a  selected from the group consisting of SiCl4, SiHCl3, SiH2Cl2 and Clxe2x80x94(SiCl2O)nxe2x80x94SiCl3(n being an integer, preferably 1 to 3).
It is preferable in this method  invention that the compound having a fluorocarbon group and chlorosilyl group is represented by a formula: CF3xe2x80x94(CF2)nxe2x80x94(R)mxe2x80x94SiXpCl3-p where n represents 0 or an integer; R represents an alkyl  alkylene group or a hydrocarbon substituted group containing Cxe2x95x90C, Cxe2x89xa1C, a silicon atom or a hydrogen atom; m represents 0 or 1; X represents a hydrogen atom, an alkyl group, an alkoxy group, a fluorine-containing alkoxy group or a fluorine-containing alkyl group; p represents 0, 1 or 2.
It is preferable in this method  invention that the compound having a fluorocarbon group and an alkoxysilane group is represented by a formula:
CF3xe2x80x94(CF2)nxe2x80x94(R)mxe2x80x94SiYq(OAxe2x80x2)3-q
where n represents 0 or an integer, R represents an alkyl  alkylene group or a hydrocarbon substituted group containing Cxe2x95x90C, Cxe2x89xa1C, a silicon atom or an oxygen atom; m represents 0 or 1; Y represents a hydrogen atom, an alkyl group, an alkoxy group, a fluorine-containing alkoxy group or a fluorine-containing alkyl group; OAxe2x80x2 represents an alkoxy group; and q represents 0, 1 or 2.
It is preferable in this method  invention that the material represented by a formula: SiXsCl4-s where X represents a hydrogen atom or an alkyl group, and s represents 0, 1 or 2; is added to a non-aqueous solvent containing a compound having a fluorocarbon group and a chlorosilyl group.
It is preferable in this method  invention that the material represented by a formula: SiY1(OAxe2x80x3)4-t where Y represents an alkyl group; Axe2x80x3 represents a hydrogen atom or an alkyl group; and t represents 0, 1 and 2; is added to solvent containing a compound having a fluorocarbon group and an alkoxysilane group.
It is preferable in this method invention that fine particles of a fluorocarbon-based polymer are dispersed in advance in either the non-aqueous solvent containing a compound having a fluorocarbon group and a chlorosilyl group or the solvent containing a compound having a fluorocarbon group and an alkoxysilane group.